Spin-density study of the silicon divacancy

The possible charge states of the silicon divacancy V-2 are studied using the local spin-density pseudopotential method. The ionic coordinates are relaxed without any symmetry constraints. We obtain the formation and binding energies as well as the ionization levels from total-energy calculations and use them to discuss several experiments. We find using the 216-atom-site supercell that V-2(0) and V-2(-) have a ''mixed'' structure that includes both pairing and resonant-bond characters, V-2(0) being more of the pairing type and V-2(-) more of the resonant-bond type. [S0163-1829(98)05327-2].